A rectangular tank 10 m x 5 m in plan and 3 m deep is divided by a partition wall parallel to the shorter wall of the tank. One of the compartments contains water to a depth of 3 m, and the other a lighter liquid of specific gravity 0.75 to a depth of 2 m. The resultant pressure thrust on the partition wall is (a) 1000 kg (b) 1500 kg (c) 2000 kg (d) 2500 kg